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Obesity may cause premature aging in the brain by mid-life, according to a study published in Neurobiology of Aging. Already connected to myriad negative health outcomes, obesity also may lead to neurodegenerative effects, an area of research that has remained relatively unexplored.

The striking similarities between the aging process and the neurological effects of obesity include increased cytokine production, pro-inflammatory markers and shortened telomere length. Cytokines and pro-inflammatory markers have been linked to cognitive decline and brain atrophy, while telomere shortening is associated with the early onset of age-related health problems.

“In short, the growing body of literature that relates common markers of aging to those observed in obesity supports the hypothesis that obesity may accelerate or advance the onset of brain aging,” wrote University of Cambridge’s Lisa Ronan, PhD, and colleagues. “However, direct studies in support of this link are lacking.”

Researchers recruited more than 500 subjects from the Cambridge area over 5 years, including 150 overweight and 77 obese subjects. In order to measure the “brain-age” of each subject, they used an imaging program called FreeSurfer to perform cortical reconstruction and measure the volume of white matter. After separating the subjects into two groups by BMI (lean and overweight), they calculated the mean difference in age between every white matter volume.

Researchers found that lean subjects have an average white matter volume of 445 cm3 at an age of 60 while overweight subjects reach that volume at an average age of 50, indicating a difference of 10 years in brain-age. In addition, a previous diagnosis of elevated cholesterol showed a negative impact on white matter volume—suggesting that other conditions related to obesity may have a role in neurodegeneration.

The authors called for additional research into the topic, while noting the study’s limitations of using BMI.

“In this study, in the absence of more direct measures of relevant health parameters, it is not clear whether our results reflect a relationship between increased adiposity and white matter volume, or whether BMI is simply a proxy for more fundamental covariates,” wrote Ronan et al.

The authors also point out that this may be one reason for increased complications and mortality for obese people with traumatic brain injuries.

“In the global climate of an increasingly aged population, with rising levels of obesity, it is critical to establish the full health impact of an increased body mass,” wrote the researchers.